The company planned to update its Mactopia Web site Tuesday to reflect the upgrade, a spokesman said. Mac users downloading what they thought was version 2.0 on Monday would have retrieved the new version instead.
The free update brings to the larger Mac community a product available to paying customers since November. While instant messaging software is typically offered at no cost by AOL Time Warner, Yahoo and other companies, Microsoft introduced MSN Messenger 2.1 as part of a paid product: Office v. X for the Mac.
Apple executives have described Office v. X as the "poster child" for Mac OS X, the company's next-generation Macintosh operating system, which is built around a Unix core. Apple unveiled Mac OS X a year ago this month but initially struggled in getting software developers to quickly adapt their applications from Mac OS 9.2 to the new operating system.
In an interview last month, Kevin Browne, general manager of Microsoft's Macintosh Business Unit (MacBU), defended the decision to hold back version 2.1 from the larger Mac community. He described that version and the earlier one as "virtually identical," adding that the company would "make a decision soon" about releasing the version with Office or as an update to the product.
"I don't know why they waited so long or say they waited so long," said Gartner analyst Michael Silver. "It's development priorities. They're committed to making Windows the best platform, and frankly, Mac is a competing platform."
Paying customers also got preferential treatment with regard to Windows Media Player for Mac OS X. The product also shipped with Office v. X, but Microsoft waited nearly two months before posting the media playback and streaming software on the Web.
The new version's support for Mac OS X potentially unlocked streaming content to thousands of Web sites that do not use Apple's QuickTime player. RealNetworks does not yet offer a Mac OS X version of either RealPlayer or RealOne products. A spokeswoman would give no firmer delivery commitment than "sometime later this year."
The approach differs from Microsoft's approach to Windows, where similar technologies are included in the operating system.
"Windows is certainly their strategic platform, and they want users to have the best experience on Windows," Silver said. "They have a Mac team that is dedicated to making sure the Mac products are really good, but certainly they're never going to have as much favour as the Windows product."
Nine states and the District of Columbia are challenging that approach to business strategy and technology in court proceedings that started Monday. The states, which chose not to sign on to an antitrust settlement between Microsoft, the Justice Department and nine other states in November, argued in court that the software giant uses the bundling of so-called middleware technologies to thwart competition. The courts have defined middleware as Web browsing, instant messaging, media playback and similar technologies.
As part of its settlement with the Justice Department, Microsoft plans to offer PC makers the ability to hide access to these middleware technologies, but the litigating states want more. Microsoft, they contend, should sell a stripped-down version of Windows, without the middleware.
The second day of what could be two months of testimony started Tuesday.
